Liquid retainer for a production system

Abstract

An apparatus includes a seabed-disposed pump that includes an inlet to receive a fluid flow and an outlet. The apparatus includes a liquid retainer that is adapted to receive a fluid flow that is produced by a subsea well. The liquid retainer selectively retains and releases liquid from the fluid flow to regulate a gas volume fraction of the fluid flow that is received at the inlet of the pump.

What is claimed is: 
     
       1. An apparatus comprising:
 a seabed-disposed pump comprising a pump inlet to receive a fluid flow and a pump outlet; 
 a liquid retainer adapted to:
 receive the fluid flow provided by a subsea well; and 
 selectively retain and release liquid from the fluid flow provided by the subsea well to regulate a gas volume fraction of the fluid flow received at the pump inlet, wherein the liquid retainer is upstream from the pump; and 
 
 a flow line to communicate a flow from the liquid retainer toward the pump along a first direction, wherein the liquid retainer comprises a liquid retainer outlet to provide a gas volume fraction regulated flow to the flow line, and the liquid retainer comprises a nozzle to introduce the gas volume fraction regulated flow into the flow line in a second direction that opposes the first direction. 
 
     
     
       2. The apparatus of  claim 1 , wherein the liquid retainer comprises:
 a vessel to store a liquid reservoir; 
 a vessel inlet to communicate the fluid flow provided by the subsea well to the vessel; 
 a vessel outlet connected to the vessel above the liquid reservoir; 
 a drain outlet connected to the liquid reservoir; and 
 a liquid retainer outlet to provide a gas volume fraction regulated flow to the pump, wherein the liquid retainer outlet is connected to the vessel outlet and the drain outlet. 
 
     
     
       3. The apparatus of  claim 2 , wherein the drain outlet has a cross-sectional flow area to supply liquid from the liquid reservoir to the liquid retainer outlet based on the gas volume fraction of the fluid flow received at the vessel inlet. 
     
     
       4. The apparatus of  claim 1 , further comprising:
 a sensor to provide a signal representing an amount of liquid in the vessel; and 
 a controller to regulate operational speed of pump in response to the signal. 
 
     
     
       5. The apparatus of  claim 1 , further comprising:
 a recirculation fluid path connected between the pump inlet and the pump outlet of the pump, wherein the recirculation fluid path comprises a choke; 
 a sensor to provide a signal representing an amount of liquid in the liquid retainer; and 
 a controller to regulate a cross-sectional flow area of the choke in response to the signal. 
 
     
     
       6. The apparatus of  claim 1 , wherein the liquid retainer comprises:
 a first vessel to store a first liquid reservoir; 
 a first vessel inlet to communicate the fluid flow provided by the subsea well to the first vessel; 
 a first vessel outlet connected to the first vessel above the first liquid reservoir; 
 a first drain outlet connected to the first liquid reservoir; 
 a second vessel to store a second liquid reservoir; 
 a second vessel inlet connected to the second vessel; 
 a second vessel outlet connected to the second vessel above the second liquid reservoir; 
 a second drain outlet connected to the second vessel and connected to the first vessel above the first drain outlet to cause liquid from the second liquid reservoir to drain into the first liquid reservoir; and 
 a liquid retainer outlet connected to the second vessel outlet and the first drain outlet to provide a flow to the pump inlet. 
 
     
     
       7. The apparatus of  claim 6 , wherein the first liquid reservoir has a first liquid height that is different than a second liquid height of the second liquid reservoir. 
     
     
       8. The apparatus of  claim 7 , wherein the second liquid from the second liquid reservoir drains into the first liquid reservoir at a rate based on a difference in the liquid heights. 
     
     
       9. The apparatus of  claim 1 , wherein the liquid retainer comprises:
 a first vessel configured to store a first liquid reservoir; 
 a first vessel inlet to communicate the fluid flow provided by the subsea well to the first vessel; 
 a first vessel outlet connected to the first vessel above the first liquid reservoir; 
 a first drain outlet connected to the first liquid reservoir; 
 a second vessel configured to store a second liquid reservoir; 
 a second vessel inlet connected to the second vessel; 
 a second vessel outlet connected to the second vessel above the second liquid reservoir; 
 a second drain outlet connected to the second vessel; 
 a flow path connected to the second vessel outlet, the first drain outlet and the second drain outlet; and 
 a liquid retainer outlet connected to the flow path to provide a gas volume fraction regulated flow to the pump inlet. 
 
     
     
       10. The apparatus of  claim 1 , wherein the liquid retainer outlet comprises an opening outside of the nozzle to communicate particulates from the liquid retainer to the flow line. 
     
     
       11. The apparatus of  claim 1 , wherein the nozzle comprises a conical nozzle or a cylindrical nozzle. 
     
     
       12. An apparatus comprising:
 a pump comprising a pump inlet and a pump outlet; 
 a recirculation path coupled between the pump inlet and the pump outlet; and 
 a flow splitter configured to receive a first flow and provide a second flow to the pump inlet of the pump, the flow splitter comprising:
 a receptacle configured to receive the first flow and retain a predetermined volume of liquid to regulate a first gas volume fraction at the pump inlet. 
 
 
     
     
       13. The apparatus of  claim 12 , wherein the receptacle comprises an opening to communicate particulates in the receptacle to the recirculation path. 
     
     
       14. The apparatus of  claim 12 , wherein the receptacle is adapted to decrease a liquid volume to cause the first gas volume fraction at the pump inlet to be less than a second gas volume fraction in the first flow received by the flow splitter. 
     
     
       15. The apparatus of  claim 12 , wherein the receptacle is adapted to increase the liquid volume to cause the first gas volume fraction at the pump inlet to be greater than a second gas volume fraction in the first flow received by the flow splitter. 
     
     
       16. A method usable with a well, comprising:
 pumping production fluid from a subsea well to a surface platform; and 
 storing and releasing liquid associated with the production flow to regulate a gas volume fraction of a fluid flow, wherein storing and releasing the liquid comprises selectively retaining and releasing the liquid with a liquid retainer upstream from a pump; and 
 
       wherein the pumping comprises:
 recirculating a portion of the fluid flow between a pump outlet and a pump inlet of the pump; and 
 controlling the portion of the fluid flow associated with the recirculation based on a fluid level in the liquid retainer. 
 
     
     
       17. The method of  claim 16 , further comprising: regulating an operational speed of the pump associated with the pumping based on a stored liquid level.